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Diuretic

Spironolactone

Brand names: Aldactone

Used in: Heart Failure Liver Disease & Cirrhosis Hypertension

Spironolactone is a mineralocorticoid-receptor antagonist (a potassium-sparing diuretic) used in heart failure with reduced ejection fraction, resistant hypertension, ascites from liver disease, and primary hyperaldosteronism.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Heart Failure: Initiate treatment at 25 mg once daily ( 2.2 ). Hypertension: Initiate treatment at 25 to 100 mg daily in either single or divided doses ( 2.3 ). Edema: Initiate therapy in a hospital setting and titrate slowly. The recommended initial daily dose is 100 mg in single or divided doses ( 2.4 ). Primary hyperaldosteronism: Initiate treatment at 100 to 400 mg in preparation for surgery. In patients unsuitable for surgery use the lowest effective dosage determined for the individual patient ( 2.5 ). 2.1 General Considerations Spironolactone can be taken with or without food, but should be taken consistently with respect to food [see Clinical Pharmacology (12.3) ] . 2.2 Treatment of …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-11-19. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It competitively blocks aldosterone at the mineralocorticoid receptor in the distal nephron, promoting sodium and water loss while retaining potassium; in heart failure it also reduces adverse cardiac remodelling.

Prescribing in practice

  • Hyperkalaemia is the key risk — check renal function and potassium before starting and after initiation or dose increase, and avoid in significant renal impairment or pre-existing hyperkalaemia.
  • Risk is higher when combined with ACE inhibitors, ARBs, potassium supplements or potassium-sparing drugs.
  • Gynaecomastia and breast tenderness can occur; eplerenone is an alternative if troublesome.

Monitoring

Monitor potassium and renal function at baseline, after starting or titrating, and periodically; review promptly during intercurrent illness.

Counselling the patient

  • Avoid potassium-based salt substitutes and over-the-counter potassium supplements.
  • Report breast tenderness or swelling, or marked tiredness.

Evidence & guidelines

Mineralocorticoid-receptor antagonists improve prognosis in HFrEF (e.g. RALES) and are recommended within guideline-directed therapy (NICE NG106).

Reference: NICE NG106 Chronic HF; RALES Trial NEJM 1999; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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